Field of the Invention
The present invention relates to wireless communication and, more particularly, to a method of performing an uplink Hybrid Automatic Repeat reQuest (HARQ) in a wireless communication system and an apparatus using the method.
Related Art
Recently, the data transfer rate over a wireless communication network is rapidly increasing. This results from the appearance and spread of a variety of devices, such as smart phones and tablet PCs which require Machine-to-Machine (M2M) communication and a high data transfer rate. In order to meet a required higher data transfer rate, Carrier Aggregation (CA) technology in which more frequency bands are efficiently used, Cognitive Radio (CR) technology, etc. are emerging. In order to increase a data capacity a limited frequency, multiple antenna technology, multiple base station cooperation technology, etc. are recently highlighted.
Furthermore, a wireless communication network is evolving into an increase in the density of accessible nodes around a user. Here, the nodes mean antennas or a group of antennas which are spaced apart from one another at specific intervals in a Distributed Antenna System (DAS). However, the nodes are not limited to this sense, but can be used as a broader sense. That is, the node can be a macro eNodeB, a pico-cell eNodeB (PeNB), a home eNodeB (HeNB), a Remote Radio Head (RRH), a Remote Radio Unit (RRU), a Relay Node (RN), or distributed antennas (or group).
A wireless communication system equipped with nodes distributed at high density can have better system performance through cooperation between the nodes. That is, if the transmission and reception of nodes are managed by one control station and thus the nodes operate like antennas or a group of antennas for one cell, the nodes can have more excellent system performance than that when the nodes operate as independent base stations without cooperation. A wireless communication system including a plurality of nodes and a base station controlling the plurality of nodes is hereinafter called a multi-node system.
Meanwhile, in a wireless communication system, a Hybrid Automatic Repeat reQuest (HARQ) is performed between a transmitter and a receiver. The HARQ is a signal transmission and reception method of checking whether or not data received from a physical layer includes an error that cannot be decoded and requesting retransmission if an error is generated. If an error is generated in a process of performing an HARQ, a receiver sends not-acknowledgement (NACK) through a control channel. If an error is not generated in the process of performing an HARQ, the receiver sends acknowledgement (ACK).
A multi-node system can also support this HARQ. In a multi-node system, however, an HARQ may not be smoothly performed using only existing control channels for ACK/NACK transmission because the multi-node system can provide service to more terminals than those of an existing wireless communication system. Furthermore, even in an existing wireless communication system, an HARQ may not be smoothly performed according to an increase in the number of supported terminals.